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Parity and subfertility effects of continuous oral contraceptive on fertility are important
LETTER TO THE EDITOR
To the Editor: In recent articles, Barnhart and colleagues (1) present data on time to conception after discontinuation of continuous oral contraceptive (OC). They compare these and other data and conclude that ‘‘the return of fertility in former OC users . is comparable to . other contraceptive methods’’ (2). Although we are pleased to see the addition of empirical evidence to this debate, we have some concerns about the role of parity in the time to conception, and are concerned that an uncritical acceptance of this conclusion may cause harm. The investigators focussed on a 12-month end point as the official time frame for infertility. However, women often approach their physicians with questions about fertility before a year has past, and, particularly for women in their 30s and 40s, clinicians must weigh the relative likelihood of infertility and decide on intervention versus watchful waiting. In this context, the observations of Gnoth et al. (3) that most truly fertile couples will conceive within 6 months, are an important clinical guideline, and it would be reasonable to start investigating possible causes of infertility (e.g., male factor, daily diary, and ovulation monitoring) after 6 months for a couple discontinuing other methods of contraception. Women and the clinicians they consult need to know that a transient delay in conception is to be expected after discontinuation of OCs. These information will reduce anxiety, and forestall unnecessary infertility workups and assisted reproduction interventions. We also remain concerned about the implications of widespread elective use of continous OCs for menstrual suppression, particularly for young women during development and before the first pregnancy. A closer examination of the data by parity (1) shows a lower rate of conception for nulliparous women (Fig. 1) particularly after 3 months when the majority (73% or 8/11) of parous women, but only 30% (3/10) of nulliparous women had conceived. It should also be noted that many women did not complete the 1-year study before seeking pregnancy, and that the study only included women 18 years or older. Conception rates after a longer duration of use, or use during reproductive development remain unclear. Finally, we wish to draw attention to the conflicts of interest. Both this review and the original article were written under contract to the pharamaceutical company, who also
0015-0282/09/$36.00
FIGURE 1 Proportion of women becoming pregnant following discontinuation of continuous use combined hormonal contraception, by duration of discontinuation, and plotted by parity: open circles: nulliparous women (n ¼ 10); closed circles: parous women (n ¼ 11). Graph drawn from data in Barnhart K, Mirkin S, Grubb G, Constantine G (2009). Conception Rates Following Discontinuation of Continous OC
% pregnant
Parity and subfertility effects of continuous oral contraceptive on fertility are important
90% 80% 70% 60% 50% 40% 30% 20% 10% 0%
Nulliparous Women (n=10) Parous Women (n=11) 6 months
3 months
12 months
Months since Discontinuation Letters to the Editor. Fertil Steril 2009.
performed the statistical analysis. An example of this bias is in the extension of reporting from 12 to 13 months, presumably to include one more pregnancy. Christine L. Hitchcock, Ph.D. Jerilynn C. Prior, B.A., M.D. Centre for Menstrual Cycle and Ovulation Research (CeMCOR), Division of Endocrinology, Department of Medicine, University of British Columbia, Vancouver, BC Canada June 18, 2009
REFERENCES 1. Barnhart K, Mirkin S, Grubb G, Constantine G, et al. Return to fertility after cessation of a continuous oral contraceptive. Fertil Steril 2009;91: 1654–6. 2. Barnhart KT, Schreiber CA. Return to fertility following discontinuation of oral contraceptives. Fertil Steril 2009;91:659–63. 3. Gnoth C, Godehardt E, Frank-Herrmann P, Friol K, Tigges J, Freundl G, et al. Definition and prevalence of subfertility and infertility. Hum Reprod 2005;20:1144–7.
doi:10.1016/j.fertnstert.2009.06.036
Fertility and Sterility Vol. 92, No. 4, October 2009 Copyright ª2009 American Society for Reproductive Medicine, Published by Elsevier Inc.
e47
To the Editor: In recent articles, Barnhart and colleagues (1) present data on time to conception after discontinuation of continuous oral contraceptive (OC). They compare these and other data and conclude that ‘‘the return of fertility in former OC users . is comparable to . other contraceptive methods’’ (2). Although we are pleased to see the addition of empirical evidence to this debate, we have some concerns about the role of parity in the time to conception, and are concerned that an uncritical acceptance of this conclusion may cause harm. The investigators focussed on a 12-month end point as the official time frame for infertility. However, women often approach their physicians with questions about fertility before a year has past, and, particularly for women in their 30s and 40s, clinicians must weigh the relative likelihood of infertility and decide on intervention versus watchful waiting. In this context, the observations of Gnoth et al. (3) that most truly fertile couples will conceive within 6 months, are an important clinical guideline, and it would be reasonable to start investigating possible causes of infertility (e.g., male factor, daily diary, and ovulation monitoring) after 6 months for a couple discontinuing other methods of contraception. Women and the clinicians they consult need to know that a transient delay in conception is to be expected after discontinuation of OCs. These information will reduce anxiety, and forestall unnecessary infertility workups and assisted reproduction interventions. We also remain concerned about the implications of widespread elective use of continous OCs for menstrual suppression, particularly for young women during development and before the first pregnancy. A closer examination of the data by parity (1) shows a lower rate of conception for nulliparous women (Fig. 1) particularly after 3 months when the majority (73% or 8/11) of parous women, but only 30% (3/10) of nulliparous women had conceived. It should also be noted that many women did not complete the 1-year study before seeking pregnancy, and that the study only included women 18 years or older. Conception rates after a longer duration of use, or use during reproductive development remain unclear. Finally, we wish to draw attention to the conflicts of interest. Both this review and the original article were written under contract to the pharamaceutical company, who also
0015-0282/09/$36.00
FIGURE 1 Proportion of women becoming pregnant following discontinuation of continuous use combined hormonal contraception, by duration of discontinuation, and plotted by parity: open circles: nulliparous women (n ¼ 10); closed circles: parous women (n ¼ 11). Graph drawn from data in Barnhart K, Mirkin S, Grubb G, Constantine G (2009). Conception Rates Following Discontinuation of Continous OC
% pregnant
Parity and subfertility effects of continuous oral contraceptive on fertility are important
90% 80% 70% 60% 50% 40% 30% 20% 10% 0%
Nulliparous Women (n=10) Parous Women (n=11) 6 months
3 months
12 months
Months since Discontinuation Letters to the Editor. Fertil Steril 2009.
performed the statistical analysis. An example of this bias is in the extension of reporting from 12 to 13 months, presumably to include one more pregnancy. Christine L. Hitchcock, Ph.D. Jerilynn C. Prior, B.A., M.D. Centre for Menstrual Cycle and Ovulation Research (CeMCOR), Division of Endocrinology, Department of Medicine, University of British Columbia, Vancouver, BC Canada June 18, 2009
REFERENCES 1. Barnhart K, Mirkin S, Grubb G, Constantine G, et al. Return to fertility after cessation of a continuous oral contraceptive. Fertil Steril 2009;91: 1654–6. 2. Barnhart KT, Schreiber CA. Return to fertility following discontinuation of oral contraceptives. Fertil Steril 2009;91:659–63. 3. Gnoth C, Godehardt E, Frank-Herrmann P, Friol K, Tigges J, Freundl G, et al. Definition and prevalence of subfertility and infertility. Hum Reprod 2005;20:1144–7.
doi:10.1016/j.fertnstert.2009.06.036
Fertility and Sterility Vol. 92, No. 4, October 2009 Copyright ª2009 American Society for Reproductive Medicine, Published by Elsevier Inc.
e47